Samsung SCH-210 service manual.pdf - Free

Circuit Description6-1-4 Audio PartTX AUDIO PATHThe voice signal output from microphone isfiltered and amplified by the internal OP-AMPand is converted to PCM data by the CODEC(U117). This signal is then applied to the MSM(U101)'s internal vocoder.RX AUDIO PATHDe-Emphasis CircuitThis circuit is 1st LPF featuring -6dB/oct to reducesignal loss and noise in Rx path.ExpanderRX AUDIO PATHThe PCM data out from the MSM is converted toaudio signal by ADC of CODEC (U117), is thenamplified by the speaker amplifier (U111) to besent to the speaker unit.FM TX PATHThe expander features 1:2 level to reduce signalloss and noise in Rx path. The zero crossing levelof the expander is 2.9 kHz/dev, attack time is 3mS, and release time is 13.5 mS.Volume AdjustVolume can be adjusted up to 4 steps for the userto obtain a proper loudness of received signal.Pre-Emphasis CircuitThe circuit features +6dB/oct to reduce signal lossand noise in Tx path.CompressorThe compressor features 2:1 level to reduce signalloss and noise in Tx path. The zero crossing levelof the compressor is 2.9 kHz/dev, attack time is3 mS, and release time is 13.5 mS.LimiterThe limiter performs to cut 0.53 Vp-p or higheraudio signal level so that the FM frequencydeviation is not over 12kHz/dev. The functionis used to avoid confusion over phone line. LPF isused to reduce a specific high frequency of limitedsignal.6-1-5 TX WBD, ST, And SATThese signals are generated from MSM. Themodulation level of TX WBD and ST is8kHz/dev, and SAT is 2kHz/dev.6-1-6 Buzzer Driving CircuitryBuzzer generates alert tone. When the buzzerreceives the timer signal from the MSM, itgenerates alert tone. The buzzer level is adjustedby the alert signal's period generated from theMSM timer.6-1-7 Key Tone GeneratorRinger signal (pin 49) out from MSM (U101) ispassed through 2 serial LPF consisting of R141,C145, R145, and C142, amplified at the speakeramp (U111), and comes out to speaker. In handsfreemode, the key tone is applied to RX audio linethrough the LPF and C153, R142.6-4 Samsung Electronics - Contents may change without notice.